Current pause in Atlantic tropical activity won't last long, expert warns

A lull in tropical activity over the Atlantic basin that began right after Isaias's demise on Wednesday is likely to last through this weekend, but the quiet conditions are not likely to last long given 2020's track record.

The Atlantic tropical season has been moving along at a blistering and at times record-setting pace this year. The 2020 season has already spawned nine tropical storms and a tropical depression. Of the nine tropical storms, two -- Hanna and Isaias -- have gone on to strengthen into hurricanes.

"Sea surface temperatures continue to run much higher than normal across the southern part of the Atlantic, much of the Gulf of Mexico and along the southeastern coast of the United States," AccuWeather's top hurricane expert Dan Kottlowski said.

"The very warm water and generally favorable winds in the middle and upper part of the atmosphere are creating lower-than-average surface pressure over much of the Atlantic basin, which in turn has created and will continue to create a favorable environment for tropical development in the long term," Kottlowski explained.

Meanwhile, a train of tropical disturbances, called tropical waves, continues to march westward from Africa. This phenomenon is referred to as the Cabo Verde season, named for the group of islands off the northwest coast of Africa. The Cabo Verde season represents the backbone of the Atlantic hurricane season with most tropical systems from late August through early October stemming from one of these tropical waves.

As of Thursday, there were no organized tropical features across the Atlantic basin with a pause in tropical activity just getting underway.

"Changes taking place this week will be brief but may last into the first part of next week and should limit tropical development over the main part of the Atlantic," Kottlowski said.

"A large high pressure area that usually resides between Bermuda and the Azores is shifting southward this week," Kottlowski said. "In turn, this will cause the belt of northeast trade winds to shift farther south and strengthen into the zone where we have the parade of tropical waves heading westward."

The pattern change will briefly increase wind shear, or the changing of winds with altitude, and the flow of dry air over the zone where many tropical systems are born. Any tropical disturbance, or tropical wave, that moves along through this zone has a high chance of being torn up and any better organized feature would tend to struggle with development.

"At some point, perhaps toward the early or middle part of next week, a more robust tropical wave may move westward and could spin something up near the Windward or Leeward islands," Kottlowski added.

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